AU511131B2 - Servo control valve actuating means - Google Patents

Description

7'C 0O, M 0 N W E A L~ T

We CANRON, INC., of c/o Su. Tg'Wfi street, New Yar] States of America,

hereby apply for the grant of a Patent~for an invention entitled:

"MECHANICAL WIYDRO SERVO.VALVE"

which is described in the accompanying cmlt specification.

The application is a convention application and is based on the application for patLent or similar protLection made

in UNITED STATES OF AMERICA 009@ 0 S on 8th February, 1977 under No. 766,672 00 in SO o @0 S 0 on 0000 APPLICATION ACCEPTED AND AM EW*NY A 5 0 0 0 *5

*0 0 *ALLOWED- 0 0 SS 0

00 @0 oraddress for service is care of DAVIES COLLISON, 0 0 0 0 Patent Attorneys, of 1 Little Collins Street, Melbourne, in the State of Victoria, Comnmonwealth of Australia.

00

00 DATED -this 31st day of January, 1978. 000

00 0 00~ 0 *o

0

*0 00 (a member of the firm of DAVIES COLLISON) 4 0 0 0 for and on behalf of -the applicant

I TO: The Commijssioner- of Patents WODEN ACT 2606 I

1*

,(CONVENTION-Company) 2P71-914 link

FORM 8-REGULATION 12 (2)

COMMONWEALTH OF AUSTRALIA 5 I EE STAMPS

PATENTS ACT, 1952-1969 DECLARATION IN SUPPORT OF A CONVENTION APPLICATION FOR A PATENT In support of the Convention Application male b

(aHeo nsr (n ul)Canron, Inc., whose full post office address is c/o Sullivan and Name of Company. Cro .well 4.8 .Wall1 S.ret Ne.or.Nw.ok (hereinafter referred to as "Applicant") for a patent for an invention entitled:

lb) Here insert ltile of CH NI A L H D S V VA

Ful Name sr and Address of Company Official authorised to m a eke ara i n of (d 325 Ellerton Ave., MOontreai, Quebec, Canada

do solemnly and sincerelyi declare as follows: 1 am authorised by Applicant to make this declaration on its behalf. 0 2. The basic Application(s) as defined by section 141 of the Act was/wave is Nero insert 6Cobrntry or Countries Basic maei in a) ntd a .nite on th h dyo th1dy9f1Lr Fbur 19.. olowed by date or a toes of B asi da 19 Sp~5licatior(s)...... on the y Hero insert Full k, Hubert Maisonneuve NamelsI of Applicantls) #1 in &Basic Country. 3. (.Hub ert Maisonneuve, of 655 Pine Ridge Drive, West Columbia, l e Insert (in full) Na n and Address of Inventor or South Carolina, United States ea cta lnrter.

is the actual Inventor(s) of the invention and Ihe facts upon which Applicant is entitled 0 td1 make the Application are as follows: I' 0 I Applicant is the Assignee of the said Inventor(s).

wa/4. The basic Application(s) referred to in paragraph 2 of this Declaration S

S *5 p S was/c the first Application(s) made in a Convention country in respect of the *5 invent ion, the subject of the Application.

DECLARED at Canada this 20th da f Jan ay17 Personal Signature h) -1 of Declarant (no soal, witness or legalitat ion).

To THE COMMISSIONER OF PATENTS.

C ~Re 1 11--31~611~2

g (11) AU-Bl-32,999/78

(12) PATENT SPECIFICATION ABRIDGEMENT (19) AU

(21) 32,999/78 511,131 (22) 3.2,78 (23) 3.2.78 (24) 8.2.77 (31) 766672 (32) 8.2.77 (33) US (43) 9.8.79 (44) 31.7.80 2 F16K E01B 35/02 (51) F16K 31/53 F16K 3/08 3/32 (54) Servo control valve actuating means (I1) Canron, Inc. (72) Maissoneuve, H. (74) DM (56) 12,002/66 420,228 74.71, 65.1 59,636/65 74.7, 83.9, 77.1, 31.9, 56.5 7,968/32 74.7 (57) Claim 1. A condition-responsive, servo control valve for controlling a variable condition of a remote element, the valve comprising a first input shaft rotatable according to a desired input condition and a second input shaft rotatable according to either the actual condition of said element or a reference condition, a differential gear train interconnecting said first and second input shafts to an output shaft, and a rotary fluid valve operably connected to said output shaft to provide a fluid output representing the difference between the conditions determining the first and second input shaft pos- itions, which output may be applied to actuator means operable to bring the actual or reference and desired input conditions into conformity.

D1 28:3

I- Ir

COMMONWEALTH OF AUS.T A" I

PATENTS ACT 1952

COMPLETE SPECIFICATION

(Original) 32 999 8 FOR OFFICE USE

Class tr~t._Class &Ifltodxenta !:Sccdcrft 49. rale und4rraus 1 i~ Appli.ation Number: '%ctin Lodged:

Complete Specification Lodged: Accepted: Published:

Priority:

Related Art:

Name of Applicant: CANRON, INC.,

Address of Applicant: c/o Sullivan and Cromwell, 48 Wall Street, New York, New York, United States of America,

Actual Inventor(s): HUBERT MAISONNEUVE

Address for Service: DAVIES COLLISON, Patent Attorneys, 1 Little Collins c-eet, Melbourne, 3000.

Complete specification for the invention entitled:

"MECHANICAL HYDRO SERVO VALVE"

The following statement is a full description of this invention, including the best method of performing it known to us

YL__I ~LIIIII

ABSTRACT OF THE DISCLO E

A hydro mechanical condition-responsive servo control

valve for controlling a variable condition, such as position or

rate of change of position, of a remote element, comprises a

rotary fluid valve controlled by a differential gear train

arranged to register differential movement between two input

shafts, one of which is connected for movement according to a

desired input condition and the other of which is alternatively

connected either to register the actual element condition or

a reference [datum] condition; the rotary valve including

mating stationary and rotary valve plates each incorporating

fluid flow ports cooperatively arranged on the mating plate

surfaces thereby to control fluid flow from a fluid inlet to a

fluid outlet in accordance with the relative position or movement

of said two input shafts.

This invention relates to a condition-responsive servo

control valve for controlling a variable condition of a remote

element. Servo control valves in general are well known but

have hitherto been of complex and sometimes frail design in

order to achieve the necessary accuracy and sensitivity of

operation.

An object of the present invention is to achieve a servo

control valve of rugged and simple mechanical construction.

This is in contrast with, say, known servo control valves,

for example, of the electro-hydraulic, analog or digital type,

which are normally controlled through a complex electronic

network of high gain amplifiers and feedback loops, which are

by nature fragile, voltage and temperature sensitive and sus-

ceptible to breakdown. Moreover, in the hydraulic circuitry

a high. degree of fluid filtration is necessary to maintain correct functioning, due to the tiny orifices employed, for example in the flapper type valve or the primary pilot control section and the square shoulder abutment of the round valve spool in the main directional section of the valve.

It is a further object of the invention to eliminate the

o disadvantages of such conventional electro-hydraulic servo

oC contr)J valve by using a solid and rigid mechanical construction, Sin which the hydraulic control valve section is resistant

to normal fluid contamination, and the effects of vibration,

impact and temperature changes.

According to the invention there is provided a condition-

responsive servo control valve for controlling a variable con-

dition of a remote element, the valve comprising a first

input shaft rotatable according to a desired input condition

and a second input shaft alternatively rotatable according to

either the actual condition of said element or a datum cond-

ition, a differential gear train interconnecting said first

and second input shafts to an output shaft, and a rotary fluid

valve operably connected to said output shaft to provide a

fluid output representing the difference between the conditions determining the first and second input shaft positions, which

output may be applied to actuator means operable to bring the

actual or reference and desired input conditions into conformity.

In practice, in order to increase the sensitivity of res-

ponse of the rotary fluid valve to movement of the first input

shaft, reduction gearing may be employed between the first

input shaft and the differential gear train. Similarly, in

order to increase the sensitivity of response of the rotary

fluid valve to movement of the second input shaft, reduction

gearing may be employed between the second input shaft and the differential gear train.

The second input shaft is operatively connected to the

element under control for closed loop control, but is isolated

from the element for open loop control and in this case may

be set to a reference position for such control.

In a practical mechanical construction, the rotary fluid

valve comprises a rotary valve plate drivably connected to the

Soutput shaft and mating with a stationary valve plate coop-

Seratively arranged therewith, the rotary and stationary valve

plates each incorporating fluid flow ports arranged in coop- erative relationship to control fluid flow from a valve inlet,

connected to a fluid reservoir, to a valve outlet, connected

to a fluid actuator operable to control the element condition,

according to the relative angular positions of the rotary and

stationary valve plates.

For example, in a suitable port configuration, the rotary

and stationary valve plates each incorporate in their mating

surfaces generally annular ports, of configuration, in part-

icular width, varying with angular position, according to the

desired output flow-rate per change in the relative angular position of the valve plates.

These valve ports may be arranged to achieve a null ref-

erence position, corresponding to no relative angular displace-

ment between the first and second input shafts, or identity

between the desired and either the actual or reference conditions

at which there is no fluid connection betwee. the fluid inlet

and outlet and thus no fluid output to the fluid actuator.

For improved sealing, the stationary and rotary valve

plates are desirably biassed together under fluid pressure from

the fluid inlet to achieve a sealing action therebetween, and

J -cc, CI

fluid is also fed between the mating surfaces thereof to reduce

rotational friction therebetween.

A mechanical spring biassing means could be used to urge

the stationary and rotary valve plates into rotational sealing

engagement.

The valve may be adapted to respond to either the absolute

O angular position of the first input shaft or the rate of change C of the angular position of the first input shaft, relative to C". C,4 the second input shaft.

In a suitable mechanical construction for the differential

gear traini there are employed two interme3hing gears, each of

mutually-opposed, coaxial, independently-rotatable level gears;

one of the gears of one pair being drivably connected to the

first input shaft and the other gear can be drivably connected to

the second input shaft; the other pair of level gears being

freely and independently rotatable about a common axis at

right angles to the common rotational axis of the one pair and

being supported in a spider so the gears of the other pair

intermesh with both gears of the one pair on opposite sides of

the rotational axis of the one pair; the spider being drivably connected to the output shaft thereby to rotate according to

differential movement between the first and second input shafts.

Desirably, mechanical biassing means is arranged to urge

the pairs of gears into mutual interengagement to minimize back-

lash therebetween and thus hysteresis in the response char-

acteristic of the valve.

Important applications of the servo control valve according

to the invention include an alignment device incorporating the

valve and in which the first iiiput shaft is connected to a

pendulum through a step-up gear means and the second input nr _IZls~ shaft is isolated from the element level and is movable according to a desired reference level; the output shaft being connected to actuator means operable to effect a level change of said element, whereby the element may be set level or at a desired inclination.

In a further application of such alignment device an

optical sight is operatively connected by adjustment means to

cn the first input shaft for sighting a reference mark on the

element to be controlled, the second inpu'- shaft being connected

to register the element position. Such alignment devices may be used in the levelling and

alignment of railway track and several of such devices may be

used cooperatively to align the track with respect to a variety

of different axes. For example, three units may be combined

and may indeed be operatively interconnected to align a track

in three dimensions.

DESCRIPTION OF PREFERRED EMBODIMENTS

The following is a description of some preferred part-

icular embodiments of the invention, by way of example only,

with reference to the accompanying diagrammatic drawings,

in which:

DESCRIPTION OF DRAWINGS

Figure 1 shows a sectional view of a condition-responsive,

servo control valve according to the invention, depicting the

layout of the principal elements;

Figures 2a, 2b, 2c ahd 2d show different configurations of

valve plates for the rotary valve shown in Figure 1;

Figures 3a, 3b, 3c and 3d show the operational character-

istics of the various valve plates shown in Figures 2a, 2b, 2c

and 2d respectively;

Figure 4 shows a general perspective view of an operational

servo control valve unit with an input control dial and feed-

back connecting link;

Figure 5 shows a general perspective view of a servo

control valve adapted for use as a level alignment device with

an input control dial and a reference pendulum feedback linkage;

Figure 6a and 6b show sectional views of part of a servo

C control valve adapted for use in an alignment device with an 6a optical sight mounted on one input shaft; Figure 7 shows an overall alignment device incorporating

the arrangements of Figures 6a and 7b; Figures 8a and 8b show a modification of the alignment

device shown in 6a, 6b and 7 for aligning railway track;

Figures 9 and 10 respectively show side and end elevations

of two alicnment devices operatively interconnected, each unit

being of the general kind shown in Figures 6a, 6b, 7, 8a, 8b,

9 and 10; and

Figures 11 and 12 show three alignment devices operatively

interconnected.

Referring to the drawings, in particular Figure i, a

condition-responsive servo control valve essentially comprises

a hydromechanical valve incorporating a rotary fluid valve

operatively connected to a mechanical drive assembly 11. The

drive assembly 11 essentially comprises differential gearing

interconnecting a first input shaft 12, a second input shaft

13 and an output shaft 14, drivably connected to operate the

rotary valve 10. Movement o. the output shaft 14 and thus

operation of the rotary valve 10 is in accordance with differ-

ential movement between the first input shaft 12 and the second input shaft 13. In order to provide a suitably scaled response characteristic for movement of the output shaft 14 with respect to differential movement between the input shafts 12 and 13, step-up gearing is employed between the first and second input shafts 12 and 13 and the differential gear assembly. The latter comprises two gear pairs, each of opposed bevel gears, the

Sopposed gears of one pair being rotatable about an axis at

C- right angles to the common rotational axis of the opposed gears

C of the other pair. Specifically, opposed bevel gears 22 and C4 C 23 of one pair are drivably connected to pinion gears 15 and

16 respectively, which in turn mesh with pinion gears 17 and 18 mounted on the first and second input shafts 12 and 13 res-

pectively. The pinion gears 15 and 16 are coaxial with the

output shaft 14, but are freely rotatable independently thereof.

In the differential gear unit the other pair of gears comprises

two opposed freely and independently rotatable coaxial bevel

gears 24 which mesh with the bevel gears 22 and 23 of the other

pair, but which are supported in a spider 19, which maintains

their common rotational axis at right angles to the cormnon

axis of rotation of the bevel gears 22 and 23 and which is

itself rotatable about the latter axis and is drivably connected

to the output shaft 14. In this way differential movement

between the bevel gears 22 and 23 is accommodated by differential

rotation of the opposed bevel gears 24 and consequent rotation

of the spider 19 about the axis of pinion gears 15 and 16 and

bevel gears 22 and 23. This rotary movement of the spider 19

is transmitted to the output shaft 14 and thence to the rotary

fluid valve

The rotary valve 10 comprises a rotary valve plate

mating with a stationary valve plate 31. Both plates 30 and 31

incorporE.te fluid flow ports connected, in the case of the 8-- 3 i rotary valve plate, to a source of fluid through a inlet port

34, and in the case of the stationary valve plate 31 to outlet

ports 35, which in turn are connected to a unshown fluid act-

uator arranged to control the element condition under control.

The configuration of fluid flow ports in the rotary and stat-

g ionary valve plates 30 and 31 is arranged so that, upon relative

rotation between the valve plates, a fluid path is opened up

between the inlet port 34 and the outlet ports 35 to allow fluid

C flow from a source of fluid under pressure to the fluid actuator.

Considering the rotary fluid valve in more detail, the

rotary ralve plate 30 is drivably connected through sliding

pins 37 to a driving plate 32 rotatable fast with the output

shaft 14 of the differential gear assembly. The shaft 14 has

an internal bore 40 for the passage of fluid from the inlet

port 34, and communicates with a narrow chamber 38 between

the driving plate 32 and the rotary valve plate 30 through

fluid passages 39 in the shaft 14. In this way fluid under

pressure is admitted to the chamber 40 and the rotary valve

plate is urged towards the stationary valve plate 31. Addit-

ional mechanical spring biasing of the rotary valve plate

towards the stationary valve plate 31 is achieved by means of

a corrugated spring (not shown)

The rotary valve plate 30 incorporates a series of ports

in an annular configuration and various alternative port con-

figurations are shown in Figures 2a, 2b, 2c and 2d with attend-

ant operating characteristics shown in Figures 3a, 3b, 3c and

3d respectively, as described later. These ports in the rotary

valve plate 30 are not clearly visible in Figure i, but cooper-

ate with the ports 41 in the stationary valve plate 31. The

mating surfaces of the rotary valve plate 30 and the stationary valve plate 31 introduce a rotational friction and this is reduced by introducing fluid under pressure from the passage into the region 42 between the stationary and rotary valve plates.

The stationary valve plate 31 is held in position in the

valve casing 45 by means of locating pins 46. An axial thrust

O)bearing 47 is provided in the valve casing 45 to support the

axial thrust of the driving plate 32 on the rotary valve plate

CT 30 and a radial bearing 48 is also provided for the driving

plate 32.

It will be appreciated from Figure 1 that re] a'ive rotat-

ion between the rotary valve plate 30 and the stationary valve

plate 31 varies the interconnection of the ports in the rotary

valvt plate 30 with the ports 41 in the stationary valve plate

31. The relationship between the ports is more readily apparent

from Figures 3a to 3d. The affect of rotation of the rotary

valve plate 30 is to vary the fluid interconnection between the

inlet port 34 and the outlet port 35. A port 36 is also pro-

vided for connection to a return path to a fluid reservoir.

Referring to Figures 2a to 2d, therc are shown various

generally annular port configurations for the rotary valve plate

Thus, in Figure 2a, two part annular opposed segments are

employed as fluid ports and these result in a sharp cutoff

for movement cf I.he rotary valve plate 30 bringing the part

annular port regions away from the port 41 in the stationary

valve plate 31. A more gradual transition betwe-n a full flow

and no flow condition is achieved by the teardrop shape port

configuration shown in Figure 2b in this case there is no

sharp cutoff but a gradual reduction and increase in fluid

flow with rotation of the rotary valve plate 30. These oper- 10 i i ational characteristics are shown in Figures 3a and 3b. A mod- ification of the teardrop shape port configuration of Figure

2b is shown in Figure 2c, providing a sharper transition bet-

ween the changing flow rates resulting from rotation between

the stationary and rotary valve plates 30 and 31, Yet another

variation is shown in Figure 2d using an increase in the number

of ports, in this case four ports at 450 angular intervals pro-

O ducing a response characteristic shown in Figure 3d. It will

Q be appreciated that the port configuration can be varied Clez according to the particular operating requirements.

Returning again to Figure i, the overall operation of the

condition responsive servo control valve is as follows:

Relative movement between the first input shaft 12 and the

second input shaft 13 produces differential movement between

the bevel gears 22 and 23 and thus rotation of the spider 19

carrying the bevel gears 24. This in turn produces rotation

of the output shaft 14 and rotation of the rotary valve plate

relative .o the stationary valve plate 31. This produces

a fluid flow from the inlet 34 to the outlets

For closed loop control of an element, the first input

shaft 12 is moved according to the desired element condition

and the second input shaft 13 is connected to the element to

register the actual element condition. In this way differential

movement between the first and second input shafts 12 and 13,

representing a difference between the desired and actual con-

ditions of the element, produces an output from the fluid port

which is fed to an unshown fluid actuator arranged to move

or adjust the element condition until the actual element con-

dition reaches the desired element condition. In this case

the second input shaft 3- will register the new element condition

11 and will result it equality between the condition registered by the firstand second input shafts 12 and 13 and thus no diff- erential movement in the differential gear assembly and no movement of the output shaft 14 from a null reference position in which the rotary fluid valve 10 is arranged to produce no

Soutput, that is there is no connection between the fluid inlet

CS) port 34 and the fluid outlet ports C S For open loop control. of an element condition, the second

anput shaft 13 is set to a reference position and control action

will be initiated when the position of the first input shaft

i2 differs from that of the second input shaft 13, i.e. whenever

the desired input condition differs from the reference condition.

In this case the null position of the rotary valve 10, that

is when there is no fluid output from the ports 35, will corr-

espond to equality between the desired and reference conditions,

i.e. when the element is Jn the reference condition.

It should be appreciated that the valve can respond to either

absolute angular position of the first an9 second input shafts

12 and 13 or to the chaige in position or speed of those

elements. The shafts 12 and 13 may be connected to register linear movement by a simple rack and pinion gear arrangement.

An example of a practical application of the valve accord-

ing to the invention is shown in Figures 4 and 5. In the servo control valve shown in Figure 4, the input shaft 12 is rotated

by means of a control knob 51 with reference to a dial 52.

The input shaft 12 carries a worm gear 55 which meshes with

a worm gear 56 rotatably fast with the bevel gear 22 of the

differential gear assembly described with reference to Figure i.

In a practical example, the drive ratio between the meshing

gears 55 and 56 is 60 to 1 so that one full turn of the knob

F-

51 through 3600 wiLl rotate the bevel gear 22 through 60 and

thus the spider 19 of the differential gear assembly will also

roate through G6, given that the seccnd input shaft 13

remains stationary. The latter is connected to a lever 58

and linkage 59 to register the actual position of the element

under control. As before, movement of the spider 19 connected

O to the output shaft 14 will rotate the rotary fluid valve and

C, apply fluid to a fluid actuator arranged to move the element under control. This movement will be registered by the feed- back lever 58 through linkage 59 and will feed back to the

differential gear through the second input shaft 13.

The first input shaft 12 need not be moved manually,

instead a motor, for example, may be Lsed to move the input

shaft incrementally through remotely controllable amounts.

A practical application of the unit such as shown in

Figure 4 is shown in Figure 5. In this case the apparatus is

used to control the operation of a railroad track continuous

lining machine. A preliminary measurement of the track is

made using, for example, a machine running ahead of the machine used to make any adjustment, and this measurement is recorded,

conveniently in digital or analog manner on a magnetic tape or

other memory. The operator of the adjustment machine would

follow the actual measurement displayed, allowance being made

for the position difference LtLween the adjustment machine and

the machine making the measurement and suitable control of the

adjustment machine would be effected by the operator to bring

the actual track position into conformity with the desired

position. This control would simply be effected hy moving the

control knob 51 with the second input shaft 13 connected to

register the actual track position. Specifically, the device may be used to adjust the level of the track in which case a reference condition is applied to the servo control valve by means of a pendulum assembly which replaces the feedback lever

58 and linkage 59 the unit operating in open loop control

conditions. Referring to Figure 5, a pivoted pendulum 60 with

a counter balance 61 at one end and a gear segment 62 at the

Or opposite end is mounted on the valve casing and is drivably connected to the second input shaft 13 through a pinion 63

C which meshes with the teeth of the gear segment 62 integral with

the pendulum 60. The pendulum 60 takes up a vertical position

and thus rotates the second input shaft 13 to a position rep-

resenting a horizontal datum or reference. The first input

shaft 12 may be moved using the control knob 51 with reference

to the calibrating dial 52 to set the track or specifically a

track rail with reference to the horizontal reference provided

by the pendulum 60. For example, in a straight length of

track it may be desirable to have the track rails at the same elevation so that the track is level whereas for a turn in the

track is desirable to bank thetrack so that one rail is higher

than the other. The unit vould be at<tached rigidly to the frame

of the machine which would be running along the track rails and

would be arranged so that the pendulum hangs vertically downwards

when the machine is running along lev,.l rails. Any deviation of

the track from this level condition is registered by a movement

of the machine running on the rails with reference to the

pendulum 60 which remains vertical. In this condition the only input is througn the second input shaft 13 and suitable sen-

sitive response is achieved bythe gearingbetween the pinion 63

and the gear segment 62. The latter may be replaced by a

direct connection, that is by pivoting the pendulum 60 directly n- upon the second input shaft 13, according to the desired res- ponse. If it is desired to achieve a change in level from the horizontal the control knob 51 may be moved with reference to the calibrating dial 52 so that the null condition of the rotary fluid valve, in which no fluid is supplied to the adjust- ment actuators is achieved when the machine runni.ng on the rails is no longer level.

C_ A device of this kind could be used in evelling Gq cY application for example on roadway construct he levell-

ing may be achieved about any desired axes, according to the mounting of the unit and the pendulum

As an example of the sensitivity of levelling operations

achievable, a 60 to 1 ratio could be used between the worm

gear 55 and the bevel gear 56 so that super elevation, that is

elevation of one rail with respect to the other, of up to 6

inches could be dialed with each one inch of super elevation

being controlled by movement of the control knob through 600,

thereby enabling very fine adjustment of super elevation. Con-

tinuous control of super elevation can readily be affected

by the operator simply moving the control knob 51 to the desired position on the calibrating dial 52 as the machine moves along

the track.

Another adaptation of the servo control unit according

to the invention is shown in Figures 6 and 6a in which an

optical sight 70 is mounted for rotation on a shaft 71 which

is in turn connected through bevel gearing 72 and a worm and

bevel gearing 73 to a shaft 74 which is con:ectable through

a connection 76 for remote control of the first input shaft

of a remotely positioned servo control valve such as that

described previously. For example, a mechanical linkage such as a flexible shaft could be used to interconnect the shaft

74 with the first input shaft of the remote servo control unit.

Adjustment of the shaft 74 can be affected using an adjustment

knob 75 mounted on one end thereof. In operation, the optical

sight 70 would be lined up with the position of the element

under control and the adjustment knob 75 would be moved to

ensure that the optical side was kept sighted upon the element.

c The adjustment movements would be transmitted through the

connection 76 and the unshown remote linkage to the remote servo

control valve to effLect the necessary movement of the element

under control to achieve the desired alignment between the

element position and the position of the sighting unit. In

this way the device could be used to direct the element under

control with respect to a fixed location or target. For

example, such a device could be used for aligning the railroad

track with respect to a series of stakes set by a track sur-

veyor so that the track follows the correct path. Similar

devices could be used to control the track elevation and the

track level as previously described. In this way three units

c-uld be used in conjunction to align the track along three

Figure 7 illustrates a compact optical sighting unit in

which the optical sight 70 is mounted directly on the servo

control unit. In this construction the worm and the bevel

gearing 73 is directly connected to the differential gear unit.

Other parts of the servo control unit correspond with those

previously described. Figures 8a and 8b illustrate a unit

adapted to register vertical movement of th'e optical sight in

addition to angular movement thereof thus enabling alignment

about two mutually perpendicular axes. Figures 9 and 10 ill-

I _y L.

ustrate how the vertical movement of the sight can be applied

as an input to one unit of a pair of adjacent units and the

angular movement of the sight can be applied to the other two

units.

Figures 11 and 12 illustrate three units combined to reg-

ister movement about three mutually perpendicular axes.

Claims (4)

1. The claims defining the invention are as follows:-

   i. A condition-responsive, servo control valve for cont-

   rolling a variable condition of a remote element, the valve

   comprising a first input shaft rotatable according to a des-

   ired input condition and a second input shaft rotatable acc-

   rz ording to either the actual condition of said element or a O reference condition, a differential gear train interconnecting Cr 0. said first and second input shafts to an output shaft, and a Cq C, rotary fluid valve operably connected to said output shaft to provide a fluid output representing the difference between the

   conditions determining the first and second input shaft pos-

   itions, which output may be applied to actuator means operable

   to bring the actual or reference and desired input conditions

   into conformity.
2. 2. A valve as claimed in Claim 1, including reduction

   gearing between said first input shaft and said differential

   gear train, thereby to increase the sensitivity of response

   of said rotary fluid valve to said movement of said first

   input shaft.
3. 3. A valve as claimed in Claim 1 or Claim 2, including

   reduction gearing between said second input shaft and said

   differential gear train, thereby to increase the sensitivity

   of response of said rotary fluid valve to movement of sa:Ld

   second input shaft.
4. 4. A valve as claimed in Claim i, wherein said rotary fluid

   valve comprises a rotary valve plate drivably connected to said

   output shaft and mating with a stationary valve plate cooper-

   atively arranged therewith, said rotary and stationary valve

   plates each incorporating fluid flow ports arranged in a

   cooperative relationship to control fluid flow from the valve i L- inlet, directed to a fluid reservoir, to a valve outlet, conn- ected to a fluid actuator operable to control said element condition, according to the relative angular positions of said rotary and stationary valve plates.

   A valve as claimed in Claim 4, wherein said rotary and

   stationary valve plates each incorporate in their mating sur-

   faces generally annular ports, of configuration, in particular 0C! width,, varying with angular position, according to the desired

   Q- output flow-rate per change in relative angular position of

   said valve plates.

   6. A valve as claimed in Claim 5, wherein said valve ports

   are arranged to achieve a null or reference position, corres-

   ponding to no relative angular displacement between the first

   and second input shafts, or equality between the desired and

   either the actual or reference condition, at which there is

   no fluid connection between said fluid inlet and outlet and

   thus no fluid output to said fluid actuator.

   7. A valve as claimed in any of Claims 4, 5 or 6, wherein

   said stationary and rotary valve plates are biassed together

   under fluid pressure from said fluid inlet to achieve a sealing

   action therebetween and fluid is also fed between the mating

   surfaces thereof to reduce rotational friction therebetween.

   8. A valve as claimed in any of Claim. 4 to 6, including

   mechanical spring biassing means arranged to urge said stat-

   ionary and rotary valve plates into rotational sealing engage-

   ment.

   9. A valve as claimed in Claim 1 wherein said gear train

   includes a plurality of intermeshing gears with mechanical

   biassing means arranged to urge them into mutual interengagement,

   to minimize backlash therebetween.

   1 -r

   A valve as claimed in Claim 1, adapted to respond to the

   rate of change of angular position of said first input shaft

   relative to said second input shaft.

   11. A, alignment device for aligning an element with res-

   pect to a horizontal reference level, and incorporating a

   condition-responsive, ser-7o control valve as claimed in Claim

   S1,said first input shaft being connected to a pendulum through cr3 O stepup gear means and said second input shaft beirc; isolated

   from the clement level condition Lnd movable according to a

   desired reference level; said output shaft being connected to

   actuator means operable to effect a level change of said

   elemenL, whereby the element may be set level or at a desired

   inclination.

   12. An alignment device, incorporating a conditlon-respon-

   sive, servo control valve as claimed in Cliim 1, for aligning

   an element with respect to a reference in a horizontal plane,

   and including an optical sight operatively connected by

   adjustment neans to said first input shaft for sighting a

   reference mark on the element, said second input shaft being

   connected to register the element position.

   13. An alignment device as claimed in Claim 11 or Claim 12,

   adapted for aligning railway track lines with respect to a

   reference.

   14. A valve as claimed in Claim 1, wherein said variable

   condition of said element comprises the element linear or

   angular position.

   A valve as claimed in Claim 1, wherein said variable

   condition of said element comprises the linear cr angular

   speed of the element.

   16. A valve as claimed in Claim 1, wherein said second input shaft is isolated at a desired reference position from the actual element condition, whereby to achieve open loo, con- trol of said element condition using said first input shaft.

   17. A valve as claimed in Claim 1, wherein said differen-

   tial cear train comprises two intermeshing pairs, each of mut-

   ually-opposed, coaxial, independently-rotatable bevel gears;

   one of the gears of one pair being drivably connected to said

   first input shaft and the other gear of that pair being

   drivably connected to said second input shaft; the other pair

   of bevel gears being freely and independently rotatable about

   a common axis at right angles to the common rotational axis of

   said one pair and being supported in a spider so that the gears

   of said other pair intermesh with both gears of said one pair,

   but on opposite sides of the rotational axis of said one pair;

   said spider being drivably connected to said output shaft,

   whereby to move in accordance with differential movement bet-

   ween said first and second input shafts.

   18 -Ie- te>--r-a-fet-?ee-d^-3f-l-0ed re-m-o- y-om-b-

   Dated this 17th day of March, 1978

   CANRON, INC.,

   by its Patent Attorneys

   DAVIES COLLISON.

   21

   a

   -mmmmmmNmmQm

   144 ~4030 36

   a a a

   0* FIG. I

   FIG. 2a FIG. 2b FIG. 2c FIG. 2d

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   FIG.2Qo FIG. 2b FIG. 2c FIG. 2d

   FIG. 3o FIG. 3b see FIG.. 3p *FIG. 3 d see 0*s 0o 0 0 *0 se a *a a. a. a. 6 a a a a a a a a a a a a a a p a a p a a a a a .aa a.. a a a a a a a a a a. a .a a. *a

   9S9SI4

   ct7

   FIG.

   55 S 555 S S S S .55 555 S S S S 5 0* S S S S S S S S 5* S S S S 5S 55 55 S. SSS S